Performance analysis of an innovative kind of two-stage piston type expansion air engine

Abstract

In small-scale compressed air energy storage system, expansion air engine is the key component. To improve the expansion air energy performance, an innovative kind of two-stage piston type expansion air engine is put forward. In this article, working principles of the new kind of expansion air engine are described. A mathematical model of the working processes is set up by analysis of the air engine. The characteristics of the expansion air engine are obtained by using the simulation technology. Results show that, first of all, with the same supply pressure, the efficiency of the new kind of expansion air engine is higher than that of the single stage expansion air engine by approximately 15%, which is about 1.31–1.56 times of that of the single stage air engine. Simultaneously, the output power of the new kind of air engine is higher than that of the single stage expansion air engine. Second, the efficiency and output power are mainly impacted by the closing angle of valve 1. Third, the bigger the cylinder diameter ratio is, the higher the efficiency is. Finally, the efficiency and output power can reach to the highest value in suitable orifice port shape.